
Four points which lie at (0,0) ; (0,2) ; (2,2) ; (2,0)

What is the figure formed?What is the area of the figure?

The given points lie on graph as per the order given in the attachment.
Which shape?
As the points lie 2 units apart from their adjacent sides. It can be a square or rhombus.
The opposite pairs of sides are also parallel to each other. The adjacent sides of the figure formed are also perpendicular to each other.
<u>Hence! the figure formed is a square.</u>
What is the area?




Answer:
1)
2)0
Step-by-step explanation:
for part 1:
Given cos(x) - cos^3(x)
= cos(x) (1- cos^2(x))
Using the identity 
= cos(x)sin^2(x)
for part 2:
given
=
Using the identity cos(a)cos(b) + sin(a)sin(b)= cos(a-b)
=
=
=
=0!
The information's given in the question are of vital importance. These information's should be very useful while getting to the desired answer of the given question.Let us now concentrate on the problem that needs to be solved.
The height of the sign that casts a shadow of 4 meters is = 5 meters
Then
The height of the tree that casts a shadow of 30 meters = (5/4) * 30 meters
= 150/4 meters
= 37.5 meters
So the tree casting a shadow of 30 meters is actually 37.5 meters in height. I hope the procedure is simple enough for you to understand.
Let

be the random variable indicating whether the elevator does not stop at floor

, with

Let

be the random variable representing the number of floors at which the elevator does not stop. Then

We want to find

. By definition,
![\mathrm{Var}(Y)=\mathbb E[(Y-\mathbb E[Y])^2]=\mathbb E[Y^2]-\mathbb E[Y]^2](https://tex.z-dn.net/?f=%5Cmathrm%7BVar%7D%28Y%29%3D%5Cmathbb%20E%5B%28Y-%5Cmathbb%20E%5BY%5D%29%5E2%5D%3D%5Cmathbb%20E%5BY%5E2%5D-%5Cmathbb%20E%5BY%5D%5E2)
As stated in the question, there is a

probability that any one person will get off at floor

(here,

refers to any of the

total floors, not just the top floor). Then the probability that a person will not get off at floor

is

. There are

people in the elevator, so the probability that not a single one gets off at floor

is

.
So,

which means
![\mathbb E[Y]=\mathbb E\left[\displaystyle\sum_{i=1}^nX_i\right]=\displaystyle\sum_{i=1}^n\mathbb E[X_i]=\sum_{i=1}^n\left(1\cdot\left(1-\dfrac1n\right)^m+0\cdot\left(1-\left(1-\dfrac1n\right)^m\right)](https://tex.z-dn.net/?f=%5Cmathbb%20E%5BY%5D%3D%5Cmathbb%20E%5Cleft%5B%5Cdisplaystyle%5Csum_%7Bi%3D1%7D%5EnX_i%5Cright%5D%3D%5Cdisplaystyle%5Csum_%7Bi%3D1%7D%5En%5Cmathbb%20E%5BX_i%5D%3D%5Csum_%7Bi%3D1%7D%5En%5Cleft%281%5Ccdot%5Cleft%281-%5Cdfrac1n%5Cright%29%5Em%2B0%5Ccdot%5Cleft%281-%5Cleft%281-%5Cdfrac1n%5Cright%29%5Em%5Cright%29)
![\implies\mathbb E[Y]=n\left(1-\dfrac1n\right)^m](https://tex.z-dn.net/?f=%5Cimplies%5Cmathbb%20E%5BY%5D%3Dn%5Cleft%281-%5Cdfrac1n%5Cright%29%5Em)
and
![\mathbb E[Y^2]=\mathbb E\left[\left(\displaystyle\sum_{i=1}^n{X_i}\right)^2\right]=\mathbb E\left[\displaystyle\sum_{i=1}^n{X_i}^2+2\sum_{1\le i](https://tex.z-dn.net/?f=%5Cmathbb%20E%5BY%5E2%5D%3D%5Cmathbb%20E%5Cleft%5B%5Cleft%28%5Cdisplaystyle%5Csum_%7Bi%3D1%7D%5En%7BX_i%7D%5Cright%29%5E2%5Cright%5D%3D%5Cmathbb%20E%5Cleft%5B%5Cdisplaystyle%5Csum_%7Bi%3D1%7D%5En%7BX_i%7D%5E2%2B2%5Csum_%7B1%5Cle%20i%3Cj%7DX_iX_j%5Cright%5D%3D%5Cdisplaystyle%5Csum_%7Bi%3D1%7D%5En%5Cmathbb%20E%5B%7BX_i%7D%5E2%5D%2B2%5Csum_%7B1%5Cle%20i%3Cj%7D%5Cmathbb%20E%5BX_iX_j%5D)
Computing
![\mathbb E[{X_i}^2]](https://tex.z-dn.net/?f=%5Cmathbb%20E%5B%7BX_i%7D%5E2%5D)
is trivial since it's the same as
![\mathbb E[X_i]](https://tex.z-dn.net/?f=%5Cmathbb%20E%5BX_i%5D)
. (Do you see why?)
Next, we want to find the expected value of the following random variable, when

:

If

, we don't care; when we compute
![\mathbb E[X_iX_j]](https://tex.z-dn.net/?f=%5Cmathbb%20E%5BX_iX_j%5D)
, the contributing terms will vanish. We only want to see what happens when both floors are not visited.

![\implies\mathbb E[X_iX_j]=\left(1-\dfrac2n\right)^m](https://tex.z-dn.net/?f=%5Cimplies%5Cmathbb%20E%5BX_iX_j%5D%3D%5Cleft%281-%5Cdfrac2n%5Cright%29%5Em)

where we multiply by

because that's how many ways there are of choosing indices

for

such that

.
So,